Hitch and coupling arrangement for automatically effecting towing hitch and fluid quick-coupler connections between a nurse tank wagon and an nh3 applicator implement

ABSTRACT

An NH 3  applicator implement is equipped with a hitch arrangement for automatically effecting a connection with a tongue of an NH 3  nurse tank wagon. A quick-connect coupler assembly is provided for connecting the transfer hose of the nurse tank wagon to the supply hose of the implement. The quick-connect coupler assembly includes a first coupler section mounted to the applicator implement for powered, guided movement into engagement with a second coupler section mounted to the tongue of the nurse tank wagon. An electro-hydraulic control system including relay logic is used to first lock the fully coupled coupler sections together and then to engage the flow of NH 3  by remote actuation of a main on/off valve located at the nurse tank.

FIELD OF THE INVENTION

The present invention relates to a hitch and coupling arrangement for automatically effecting hitch and quick-coupler connections between a nurse tank wagon carrying a tank of anhydrous ammonia (NH₃).

BACKGROUND OF THE INVENTION

Modern farming practices in North America require the application of fertilizer in order to maximize crop yields and, in turn, maximize profits. Currently, approximately 40% of this fertilizer is applied as anhydrous ammonia (NH₃) since it is the most cost effective per unit of nitrogen. However, despite this cost advantage, the use of NH₃ has not changed significantly in the past few decades due to safety issues and the extra labor involved in a applying the NH₃. Historically, conventional knife injection applicators have been used to apply the NH₃ in the ground. These applicators generally tow a 1000-1500 gallon NH₃ nurse tank. Multiple NH₃ wagons are used to support each applicator. When the tank borne by the wagon being towed by the applicator becomes empty, it is exchanged with a wagon bearing a full tank. A tender truck hooks up to wagon bearing the empty tank in the field and transports it to a central fill station and then transports the wagon with the newly filled tank back to the field for the applicator to use. The current tank change operation is a multi-step process which requires the operator to physically dismount the tractor, put on NH₃ safety garb and/or equipment and walk back to the just emptied tank to manually bleed and disconnect the tank. Typically, conventional applicators have to change tanks every 1½ hours and the process can take up to 15 minutes with the operator being exposed to a small amount of NH₃ vapor, hence the requirement for the safety garb and/or equipment. This manual tank change operation is inconvenient to the operator and reduces the overall productivity of the applicator.

It is a trend in farm equipment of various types to make units larger in order to more quickly cover the ground. However, an applicator which has the capability to apply NH₃ at nearly twice the speed of a conventional applicator would require the tanks to be exchanged nearly twice as often, or once every 45 minutes. Employing the conventional manual change regimen, the down time involved in exchanging empty with full tanks would result in the large unit only operating only at 75% efficiency.

The problems to be addressed then are those of reducing the amount of time required for exchanging empty with full tanks of NH₃ while reducing exposure of the operator to NH₃.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a hitch and coupling arrangement for effecting automatic towing hitch and fluid quick-coupler connections between an anhydrous ammonia nurse tank wagon and an anhydrous ammonia applicator implement.

It is an object of the invention to reduce the time necessary for exchanging an empty anhydrous ammonia tank towed by an anhydrous ammonia applicator implement with a full tank while minimizing the exposure of an operator to anhydrous ammonia that might be vented or spilled during the exchange process.

The aforementioned object is achieved by providing a remotely operable arrangement effecting decoupling of a fluid quick-coupler and implement hitch so as to disconnect the implement from an empty tank of NH₃ and for subsequently effecting coupling of the quick-coupler and implement hitch so as to connect the implement to a full tank of NH₃. More specifically, there is provided a first coupler section of the quick-coupler that defines a receptacle for receiving an insert defined by a second coupler section of the quick-coupler, the first coupler section being mounted to a carriage mounted at the rear of the applicator implement for powered fore-and-aft movement toward and away from the second coupler section which is supported on the tongue of the NH₃ tank wagon. The quick-coupler sections include cooperating guide elements for guiding them together during coupling and are provided with cooperating, remotely operable, detent elements for selectively locking the coupled first and second coupler sections together or for releasing the detent elements for permitting the coupled sections to be separated from each other.

This and other objects of the invention will become apparent from a reading of the ensuing description together with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a right rear perspective view showing an anhydrous ammonia applicator implement coupled for towing an anhydrous ammonia nurse tank wagon, and showing first and section coupler sections of a quick-coupler assembly prior to being automatically coupled together.

FIG. 2 is an enlarged view of that portion of FIG. 1 which shows the mechanism for automatically effecting coupling of the first and second quick-coupler sections.

FIG. 3 is a side view of the mechanism for automatically effecting coupling of the first and second quick-coupler sections, with part of the guide ramp removed to reveal the cylinder connection with the carriage carrying the first coupler section.

FIG. 4 is a vertical sectional view taken lengthwise through the quick-coupler with the first and second coupler sections being shown in a separated condition occurring at initial contact of the first coupler section with the second coupler section during coupling the quick-coupling sections together.

FIG. 5 is a view like FIG. 4, but showing the quick-coupler sections locked together, with the poppet valves being shown in a closed condition preventing flow through the quick-coupler.

FIG. 6 is a view like FIG. 5, but showing the quick-coupler approaching the operating condition, with the poppet valves open permitting flow through the quick-coupler.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, there is shown an anhydrous ammonia applicator implement 10 coupled for towing an anhydrous ammonia nurse tank wagon 80. The applicator implement 10 is here shown as a winged implement including a center section 12, having right- and left-hand wing sections 14 and 16, respectively, hinged to its opposite sides for swinging vertically between lowered working positions, as shown, and raised transport positions, with right- and left-hand hydraulic lift cylinders 18 and 20 being provided for selectively moving the wing sections between their working and transport positions.

The center section 12 is equipped at its front with attachment points for a tractor three-point hitch, with only the upper attachment point 22 being visible. A transverse support beam 23 is located at a rear region of the center section 12 and a pair of ground wheels 24 is caster-mounted to opposite ends of the beam 23. Supported from a central region of the beam 23 is a towing hitch structure 26 which extends down and to the rear from the beam 23 and includes a generally funnel-shaped, rearwardly opening tongue receptacle 28

Referring now also to FIG. 2, it can be seen that a flexible NH₃ supply hose 30 has one end coupled to a manifold arrangement 31 which is coupled to a plurality of individual feed lines (not shown) which respectively distribute the NH₃ to each of a plurality of soil opener arrangements 32 provided in transversely spaced relationship to each other across the width of the implement 10. For a reason explained below, the supply hose 30 includes a relatively long length which is formed into a loop 33 that goes through an eye of a hose guide 34 located at a front, center region of the center section 12. The supply hose 30 extends to the rear from the guide 34 and over a transversely extending, inverted U-shaped hose support 35 having legs fixed to a tool bar of the center section 12, with the hose 30 extending first leftward at the front of guide 34 and then rearward beneath the hose support 35.

A fluid quick-coupler assembly 100 (FIGS. 4-6) is provided for interconnecting the fluid supply hose 30 to a flexible fluid transfer hose 36 leading from a nurse tank 38 carried by a wheeled wagon frame 40 of the nurse tank wagon 80. The fluid quick-coupler assembly 100 includes a first fluid coupler section 110 connected to a rear end of the fluid supply hose 30, and a second fluid coupler section 230 connected to a front end of the fluid transfer hose 36.

A guide track assembly 42 is mounted to a central location of the support beam 23 so as to be centered above the hitch assembly 26. The guide track assembly 42 comprises right- and left-hand parallel, vertical plates 44 and 46, respectively, which are each provided with a forward end region 48, which is generally rectangular and has a lower out-turned flange 50 which overlies the support beam 23 and is secured thereto by a U-bolt 52. Each plate 44 and 46 further includes a rear region 54 having only about one-third of the height of the front region 48 and being joined to and inclined downwardly and to the rear from an upper rear part of the front region 48. Fixed to each of confronting faces of the plates 44 and 46 is an edge of a guide track 56 including a horizontal section spaced a short distance below an upper edge of forward end region 48 and a downwardly and rearwardly inclined section space a short distance below an upper edge of the inclined rear region 54. A transverse plate 58 is fixed to the top edge of the plates 44 and 46, and, fixed to an inside region of the inclined portion of each transverse plate 58 is a vertical guide strap 60. The respective guide tracks 56 are spaced from each other so as to define a gap between them. A carriage 62 comprising a channel-shaped body 64 disposed with depending flanges at its opposite sides, with front and rear sets of rollers 66 being mounted to the flanges is mounted for rolling fore-and-aft along the guide tracks 56. Movement of the carriage 62 along the guide tracks 56 is selectively achieved by operation of an extensible and retractable hydraulic actuator 68 having its rod end coupled to a connecting ear 70 provided at a front underside location of the carriage 62 so as to extend downwardly through the gap provided between the guide tracks 56. The cylinder end of the actuator 68 is coupled to a frame member 72 of the center section 12 of the applicator implement 10.

The first fluid coupler section 110 is connected, in a manner described below, to a vertical mounting plate 74 of an L-shaped mounting structure 76 having a horizontal mounting plate 78 joined to the bottom of vertical plate 74 and overlying and being fixed to the carriage 62. Thus, extension of the actuator 68 from its retracted position shown in FIGS. 2 and 3 will result in the carriage 62 rolling forwardly along the guide tracks 56.

The nurse tank wagon 80 includes a tongue 82 coupled at the forward end of the wagon frame 40, the tongue 82 including a forward end defined by a circular coupling ring 84 located within the tongue receptacle 28 and receiving a retractable hitch pin (not shown) located within a clevis structure 86. A single-acting hydraulic actuator 87 is coupled to a linkage, partially shown at 88, which is attached to the hitch pin, with retraction of the actuator effecting the withdrawal of the hitch pin from the coupling ring 84, with a compression spring (not shown) being located within the actuator cylinder and acting against the piston to extend the rod so as to normally retain the pin in its hitching position within the coupling ring 84. A support stand 89 is pivotally coupled to the tongue 82 by a pivot pin 90 located adjacent a bottom lip 91 of the tongue receptacle 28, the lip 91 acting to fold the stand 89 from an upright, support position, wherein a foot of the stand is in ground engagement, to an elevated stored position, as shown, wherein the stand 92 extends backward along an underside of the tongue 82 from the pivot pin 90. Fixed to, and extending above, the tongue 82 is a hose support structure 92 including a base defining an upright receptacle receiving a post 93 having a connecting bracket 94 at its top to which opposite side straps 95 of a hose cradle 96 is pivotally connected as at pivot connections 97, which define a transverse horizontal pivot axis. Defining a front end of the cradle 96 is a front, generally U-shaped rod 98 having upwardly diverging legs fixed to forward ends of the straps 95. Similarly, a rear end of the cradle 96 is defined by a rear, generally U-shaped rod 99 having diverging legs fixed to rearward ends of the side straps 95. The cradle 96 is sloped upwardly towards the front so as to have an inclination approximately the same as that of the inclined section of the guide tracks 56. The supply hose 36 in the hose cradle 96, with the fluid coupler section 230 being located just in front of the U-shaped rod 98 at the forward end of the cradle so as to be substantially axially aligned with the coupler section 110 when the latter, together with the carriage 62, is positioned on the sloped part of the guide track 56, 56 by extension of the actuator 68. In a manner described in more detail below, the hydraulic actuator 68 may be operated remotely during the process for effecting the coupling and decoupling of the quick-coupler assembly 100 by respectively bringing the coupler section 110 into engagement with the coupler section 230, or by separating the coupler section 110 from the coupler section 230.

Referring now to FIG. 4, the quick-coupler 100 is shown in an uncoupled condition with the first and second coupler sections 110 and 150 being in axial alignment with, but with fluid conveying parts being separated from, each other. Specifically, the first coupler section 110 includes a central fluid passage 112. Starting from the left in FIG. 4, the first coupler section 110 comprises a lock arrangement support 114 and a valve housing 116, which are configured substantially as cylindrical tubes and have ends screwed together to form a single unit. The interior of the valve housing 116 is provided with an annular inward projection defining a leftwardly facing valve seat 118 and a rightward facing bottom of a cylindrical receptacle 120, which is adapted for receiving an end portion of the second coupler section 230, as described in further detail below. Located centrally within the valve housing 116 is a poppet valve head 122 including a bulbous left end section 124 joined to a rightwardly projecting stem section 126 and carrying an annular seal 128 held in sealed engagement with the seat 118 by a coil compression spring 130 acting between a bottom end of a blind bore 132 extending axially in the left end section 124 of the valve head 122 and a valve head guide 134 received in the bore and anchored to a guide support 136 retained within a right end region of the lock arrangement support 114 by a snap ring 138.

The exterior of the locking arrangement support 114 includes a left end region 140 having a first diameter, a middle region 142 having a second diameter slightly smaller than that of the left end region, and a right end region 144 having a third diameter substantially less than that of the middle region thereby defining an annular stop surface 146 facing rightward. A locking arrangement 150 is mounted for shifting axially along the support 114 and valve housing 116 and includes a lock control collar 152 received on the support 114 and having an interior surface including a left end region 154 and a middle region 156 respectively sized for sliding along the left end and middle regions 140 and 142 of the locking arrangement support 114. Since the inside surface of the left end surface region 154 is stepped outwardly from the inside diameter of the middle surface region 56, an axially facing surface 158 is defined at the juncture of the different inside diameters. A fluid passage 160 extends between a port 162 located in an end surface of the housing support 114 and an exit point located at the juncture of the different outside diameter surfaces of the left and middle regions 140 and 142 of the support 114. Thus, when a source of pressurized fluid is coupled to the port 162, the pressure will act against the surface 158 and cause the collar 152 to shift to the right, as shown in FIGS. 4 and 5, for example. The collar 152 further includes a relatively short right end region 164 having an inside diameter that is less than that of the middle region 156, thereby defining an annular, leftward facing stop surface 166 located in confronting relationship to the stop surface 146 provided on the locking arrangement support 114, with the stop surfaces 146 and 166 becoming engaged with each other, as shown FIG. 6, in the absence of fluid pressure at the port 162.

The locking arrangement 150 further includes a hollow, generally cylindrical spring housing 168 having a left end wall defined by a circular ring 169 having an inside diameter engaged with a cylindrical outer surface of the collar 152, with a snap ring 170 being mounted in a groove provided in the collar 152 adjacent its left end for the purpose of engaging the ring 169 and causing the housing 168 to be shifted rightward when the collar is shifted rightward. A spring force adjustment ring 171 is received on the locking arrangement support 114 at a location adjacent the valve housing 116. A coil compression spring 172 is located in the housing 168, with opposite ends of the spring 172 being in engagement with the end wall ring 169 and the adjustment ring 171. The housing 168 extends axially to the right from the snap ring 170 and has a right end wall defined by a support hub 174 received on the valve housing 116 and having a threaded right end screwed onto a threaded left end of a tubular detent ball carrier 176 that projects to the right beyond a right end of the valve housing 116. A plurality of angularly spaced funnel-shaped, detent ball receptacles 178 are arranged in a vertical plane traversing the ball carrier 176 at a location adjacent its right end, and each receptacle 178 contains a detent ball 180. An exterior surface of the ball carrier 176 includes a left end region 182 having a diameter slightly less than that of a right end region 184, the later containing the ball receptacles 178. A detent ball lock/release collar 186 includes respective interior surface regions 188 and 190, sized for respectively sliding along the exterior surface regions 182 and 184, with it being noted that due to the fact that the surface region 188 is at a lesser diameter than the surface region 190, an annular, rightwardly facing surface 192 is defined at the juncture of the two regions. A port 194 is provided in the collar 186 in communication with the surface 192. An annular ball-release groove 196 is provided in the interior surface region 190 of the collar 186 at a location adjacent its right end. When a source of pressurized fluid is coupled to the port 194, the collar 186 is shifted to a leftward, ball release position, as shown in FIG. 4, wherein the ball-release groove 196 is positioned in register with the detent balls 180 so as to permit them to move freely radially outward. When the detent ball lock/release collar 186 is in its release position, shown in FIG. 4, a coil compression spring 198, which encircles the hub 174, is compressed between the collar 186 and the hub 174. Upon pressurized fluid being released through the port 194, the spring will act to shift the collar 186 to the right to a locking position wherein the right end of the collar 186 is shifted into engagement with a snap ring 200 provided in a groove located adjacent the right end of the ball carrier 176, the ball-release groove 196 then being in a locking position, as shown in FIG. 5, wherein it is misaligned to the right of the detent balls 180.

A valve coupler section alignment arrangement 202 is supported at the left end region of the detent ball lock/release collar 186. Specifically, the left end of the collar 186 is defined by a flange 204 and the alignment arrangement 202 includes the vertical support plate 74 of the mounting structure 76, the plate 74 being received on the collar and clamped against the flange 204 by a threaded ring 208 engaged with a threaded section of the exterior of the collar. Three identical, axially extending, cylindrical rod guides 210 (only two shown in FIG. 2) are equally spaced from each other angularly about the collar 186 and have reduced diameter end sections 212 inserted, from the right, through holes 214 provided in the plate support plate 74. The reduced diameter end sections 212 of each rod guide 210 is threaded and receives a retaining nut 216 which secures the rod guide to the plate. Extending axially through each rod guide 210 is a bore 218 in which a rod 220 is received for sliding, with a nut 222 being threaded onto the left end of the rod for preventing it from being withdrawn rightward from the rod guide 210. Each of the rods 220 has a threaded right end engaged with a threaded bore provided in a centering plate 224 that is disposed parallel to the support plate 74. The centering plate 224 has a thickened center region that is provided with a frusto-conical opening 226 oriented with its large diameter to the right. Received on each of the rods 220 and having a left end portion encircling each of the rod guides 210 is a coil compression spring 228 having its opposite ends engaged with the plates 74 and 224, the arrangement of the rods 220 and springs 228 permitting the guide plate 224 to be resiliently deflected to non-parallel positions relative to the plate 74 during the operation of aligning the first and second sections 110 and 230 of the quick-coupler arrangement 100 with each other, in a manner described below in further detail.

The second quick-coupler section 230 includes a central fluid passage 232 and is comprised of a centering guide 234 and a valve housing 236 having threaded ends screwed together to form a single unit. Located at a central region between opposite ends of the centering guide 234 is a frusto-conical guide surface 238, which has a small diameter end joined to a step which defines an axially facing, annular stop surface 240. The exterior of the valve housing 236 is provided with an annular detent groove 242 spaced a predetermined distance from the stop surface 240. The guide surface 238 is shaped complementary to the opening 226 provided in the guide plate 224 carried by the first quick-coupler section 110.

The valve housing 236 is formed substantially as a cylindrical tube having an exterior wall which is stepped between its opposite ends so as to define a cylindrical insert section 244 sized to fit closely within the receptacle 120 of the first quick-coupler section 110, the insert section 244 terminating at an axially facing, annular seal 246 with an o-ring secured in position by an attachable o-ring keeper or collar 247. The seal 246 is disposed for contacting an end surface of the receptacle 120 and acting as a stop when the quick-coupler is in the operating flow condition (the operation condition is being approached as illustrated in FIG. 6). The collar 247 maintains the o-ring firmly in place, even when the o-ring is frozen to the abutting valve housing 116 as a result of the cooling action of NH₃. An annular valve seat 248 is formed on an interior surface of the valve housing 236 at a location where the insert section 244 joins the remainder of the valve housing 236.

Located centrally within the valve housing 236 is a poppet valve head 250 including a bulbous right end section 252 joined to a leftwardly projecting stem section 254 and carrying an annular seal 256 held in sealed engagement with the seat 248 by a coil compression spring 258 acting between a bottom end of a blind bore 260 extending axially in the right end section 252 of the valve head 250 and a valve head guide 262 received in the bore and anchored to a guide support 264 retained within a left end region of the centering guide 234 by a snap ring 266.

In operation, assume that an operator of a tractor hitched to the applicator implement 10 is notified by a signal sent by a tank pressure sensor, for example, of the fact that the nurse tank wagon 80 being towed by a semi-mounted applicator implement 10 has just become depleted of NH₃. Also assume that a tender truck operator has left a filled exchange nurse tank wagon 80 in a generally level exchange site in the field and has opened the main on-off NH₃ valve on the wagon to prepare for connecting the tank to the applicator implement 10. The operator will then drive the tractor to the exchange site and, without leaving the seat of the tractor, will actuate the hitch pin actuator 87 to withdraw the hitch pin from the drawbar coupling ring 84. After separation of the coupler sections 110 and 230 as described in detail below, the operator will pull forward, and the support stand 89 of the nurse wagon hauling the depleted tank 38 will drop to support the ring 84 in position for automatic coupling to the tender truck hitch. The tender truck driver closes the main on-off NH₃ valve on the depleted wagon upon pick up for refilling.

The carriage operating cylinder 68 on the depleted wagon 80 will initially be in an extended condition with the carriage 62 located on the inclined section of the guide track 56, 56 and the quick-coupler assembly 110 will then be in a coupled operating condition illustrated in FIG. 6 wherein the coupler sections are locked together and wherein the poppet valve heads 122 and 150 are in open conditions permitting flow through the quick-coupler assembly 110. Further it is noted that the spacing between the valve head guides 134 and 136 is at a minimum with the stem section 126 of the valve head 122 being engaged with the stem section 254 of the valve head 250, and with the valve stem guides 134 and 262, respectively, being nearly in contact with the bottoms of the blind bores 132 and 260. Further it is noted that a substantial length of the springs 130 and 258 is compressed. At this point the pressure control ports 162 and 194 are both connected to sump. As can be appreciated from the drawing figures, the poppet valve heads are recessed to avoid damage and inadvertent opening of the lines.

To prepare the coupler sections 110 and 230 for being separated from each other when in the operating condition shown in FIG. 6, the operator will then actuate an electronic control (not shown), the electronic control containing relay logic, for example, which will operate automatically in a de-couple mode so as to automatically control the separation of the quick-coupler arrangement 100. Specifically the relay logic of the electronic control first sends a signal to actuate a first control valve (not shown) to cause hydraulic fluid pressure to be coupled to the port 162 to cause the detent ball carrier 176 to be shifted a short distance bringing the right end of the carrier 176 against the stop surface 240 of the centering guide 234, as shown in FIG. 5. This small movement is sufficient to relieve the force exerted by the springs 172 on the captive detent balls 180. After a short interval, the logic program sends a signal for actuating a second fluid control valve to cause fluid pressure to be coupled to the port 194 for causing the detent ball lock/release collar 186 to be shifted to the left against the force of the springs 198 so as to place the ball release groove 196 in register with the detent balls 180, as shown in FIG. 4. The relay logic of the electronic control then sends a signal for actuating a hydraulic valve for effecting retraction of the carriage actuator 68 to cause the receptacle section 120 of the valve housing 116 to be withdrawn from about the insert section 244 of the valve housing 236. Initial movement of the coupler section 110 will result in the valve guide 134 becoming separated from the valve guide 262, with the springs 130 and 258 extending so as to initially maintain the valve head stem sections 126 and 254 in contact with each other. Just before the detent ball carrier 176 moves away from the stop surface 240, the separation of the valve guides 134 and 262, and the valve housing sections 120 and 244 will reach a point where the valve stems 126 and 254 separate from each other, with the result that the valve seals 128 and 252, respectively, become engaged with the valve seats 118 and 248, as shown in FIG. 5. Continued separation of the quick-coupler sections 110 and 230 will eventually result in the separated condition shown in FIG. 4. At this point, the relay logic of the electronic control will send respective signals causing operation of the respective control valves so that the fluid pressure at the ports 162 and 194 is vented. When the hydraulic actuator 68 becomes fully retracted, a sensor (not shown) will send a signal deactivating the control valve so that a neutral condition is obtained. The operator will then drive the tractor to pull the implement 10 away from the empty nurse wagon 80.

Next, the operator will back the tractor together with the applicator implement 10 so as to receive the coupling ring 84 at the front of the tongue 82 of the replacement nurse tank wagon 80. The lip 91 raises the stand 89 into the storage position. At this point the coupling ring 84 will be properly located in the clevis structure 86 for having the hitch pin installed and this will be done by operating a control valve for relieving the pressure from the actuator 87, with its internal spring acting to insert the hitch pin through the coupling ring to secure the ring to the clevis structure 86. The operator will then initiate a coupling mode of the electronic controller, the latter sending a signal to the first and second control valves for coupling fluid pressure to the ports 162 and 194. This will result in the lock control collar 152 shifting forwardly, thereby, in turn, effecting forward shifting of the detent ball carrier 176, and will cause leftward movement of the detent ball lock/release collar to its release position, all as shown in FIG. 4. The operator then actuates the hydraulic control valve to effect extension of the actuator 68 so as to cause the coupler section 110 to be carried rearward by the carriage 62. As the carriage 62 travels down the inclined portion of the guide track 56, 56, the centering plate 224 will eventually come into contact with the guide surface 238 of the centering guide 234. Any slight misalignment of the coupler sections 110 and 230 will be accommodated by the centering plate 224 being deflected by the interaction of the centering guide surface 238 and the frusto-conical opening 226 of the centering plate 224, with the coupler section 230 tilting, if necessary, about the axis defined by the connection pins 97. Upon the surfaces 226 and 228 becoming engaged with each other, as shown in FIG. 4, the coupler sections 110 and 230 will be properly aligned for being connected together.

With reference to FIG. 4, continued extension of the actuator 68 will cause the mounting plate structure 76 to travel towards the coupler section 230 with the result that the mounting plate 74, together with the rod guides 210, are slid to the right along the rods 220 against the action of the springs 228, while the detent ball carrier 176 moves along the exterior of the valve housing 236 until the detent balls 180 drop into the detent ball groove 242. At this point the electronic control will send a signal actuating the second fluid control valve so that it vents the fluid pressure from the port 194, thus permitting the loaded springs 182 to shift the lock/release collar 186 to its rightward locking position, shown in FIG. 5, wherein it retains the detent balls 180 in the ball groove 242. Still further extension of the carriage actuator 68 will result in the receptacle section of the valve housing 116 moving completely over the insert section 244 of the valve housing 236. During this movement, which begins with the receptacle section 120 and insert section 244, as illustrated in FIG. 5, and ends with the receptacle section 120 and valve section 244, as illustrated in FIG. 6, the stems 126 and 254, respectively of the poppet valve heads 122 and 250 from their closed positions shown in FIG. 5 to their open positions shown in FIG. 6.

To complete the coupling process, the electronic controller acts to actuate the first control valve so that fluid pressure is vented from the port 162 so that the spring 172 acts to shift the housing 168 to the left so as to cause the detent ball carrier 176 to exert a retention force on the detent balls 180, as shown in FIG. 6. The quick-coupling arrangement 110 is then coupled together, with the poppet valve heads 122 and 250 being open to permit free flow between the fluid transfer hose 36 and the fluid supply hose 30. The operator will then drive to the location in the field where application was halted due to the first nurse tank becoming empty and will commence operation with the semi-mounted applicator implement 10 and the towed nurse tank wagon 80.

It will be appreciated then that an operator can easily and quickly exchange an empty nurse tank wagon 80 for a full nurse tank wagon, while minimizing the exposure of the operator to any anhydrous ammonia liquid or gas during the exchange process. The coupling structure described above provides for automatic decoupling to prevent hose breakage and NH₃ loss if for any reason, such as a broken hitch connection, an excessive pull is exerted between the transfer and supply hoses. As can be appreciated from the description, the free states of the coupling structures define locked conditions so that hydraulic system pressure loss does not result in implement hitch or fluid coupler disconnection. Because the hitch coupling structure is activated before the hose coupling structure, relative hose positions are well defined and repeatable for a uniform, predictable coupling procedure. The coupling structure provides a unique integrated hydraulic control of the coupler flow and hose attachment. The actual final fluid connection between the hoses can be completed while the operator drives from the exchange site to the field position to thereby decrease the amount of time necessary to make the exchange. Because the volume between the coupler portions on the hoses is relatively small, only a few milliliters (about nine cubic inches) of NH₃ will be exhausted to atmosphere during coupling and uncoupling. However, a shield may be placed adjacent the couplers to prevent the exhaust from traveling in a particular direction.

Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims. 

1. A hitch and coupling arrangement for automatically hitching an anhydrous ammonia nurse tank wagon for being towed by an applicator implement and for interconnecting a first coupler section located at one end of a nurse tank transfer hose and a mating second coupler section located at one end of an applicator implement supply hose so as to form a fluid coupler assembly permitting the flow of ammonia from the nurse tank to the applicator hose, the improvement comprising: said applicator implement including: a rearwardly opening tongue receptacle fixed at a given height above the ground for receiving a forward end of a tongue of said nurse tank wagon; a fore-and-aft extending guide track mounted above said tongue receptacle; a carriage being mounted for movement along said guide track; said first coupler section being mounted for movement with said carriage, with said supply hose being flexible and of a length sufficient for permitting said carriage to move freely along said guide track so as to move said first coupler section along a coupling path; and a reversible power device being coupled to said carriage for selectively moving the carriage along said guide track; and said nurse tank wagon including: a tongue having a forward end defined by a tongue coupler, and having a support stand mounted for selective movement between a retracted stored position, wherein it extends along a remaining portion of said tongue and an extended position, wherein it supports said tongue coupler at least approximately at said given height above the ground; said first and second coupler sections being constructed for becoming locked together to form said fluid coupler assembly when said first and second coupler sections are forced together; and a hose support being coupled between said tongue and said hose at a region adjacent said second coupler section and supporting said second coupler section in substantial alignment with said coupling path, whereby, once said tongue coupler is received in said receptacle, said power device may be operated to bring said first coupler section into locked engagement with said second coupler section,
 2. The hitch and coupling arrangement, as defined in claim 1, wherein said guide track is centered above said tongue receptacle.
 3. The hitch and coupling arrangement, as defined in claim 1, wherein said guide track includes a horizontal rear section joined to a downwardly and forwardly inclined front section.
 4. The hitch and coupling arrangements as defined in claim 1, wherein said power device is an extensible and retractable hydraulic actuator having one end coupled to said carriage, and an opposite end coupled to a frame member of said implement.
 5. The hitch and coupling arrangement, as defined in claim 4 wherein said guide track includes first and second plates disposed in transversely spaced, parallel relationship to each other; first and second horizontal track members being respectively fixed to, and projecting toward each other from, said first and second plates, with a gap being left between said track members; said carriage having rollers engaged with said track members and a connecting leg depending through said gap and coupled to said hydraulic actuator.
 6. The hitch and coupling arrangement, as defined in claim 1, wherein said first and second coupler sections respectively include first and second guide surface structures mounted for becoming engaged with one another as the first coupler section moves toward said second coupler section so as to effect a mating alignment between said first and second coupler sections.
 7. The hitch and coupling arrangement, as defined in claim 6, wherein said first guide surface structure is a plate having a guide surface defined by a frusto-conical opening provided at a central location in said plate, and said second guide surface structure having a mating surface defined by an frusto-conical exterior surface.
 8. The hitch and coupling arrangement, as defined in claim 6, wherein one of said first and second guide surface structures is suspended by a spring biasing structure which yieldably retains said one of said first and second guide surface structures in a centered position.
 9. The hitch and coupling arrangement, as defined in claim 7, wherein said first guide surface structure is a guide plate having a guide surface defined by a frusto-conical opening provided at a central location of said guide plate; a biasing structure coupled between said first coupler section and said guide plate comprising an upright plate fixed to said first coupler section in parallel relationship to said guide plate; a plurality of guide rods extending parallel to a central axis of said frusto-conical opening and having first ends coupled to said guide plate; said upright plate having a plurality of holes respectively receiving said plurality of rods for sliding therein; a plurality of retaining nuts being respectively received on said plurality of rods for preventing the rods from being withdrawn from said holes in said upright plate; and a plurality of coil compression springs being respectively located on said plurality of rods and being located between said guide plate and said upright plate, whereby said guide pate may be deflected but of parallel relationship with said upright plate during engagement of said frusto-conical opening with said frusto-conical exterior surface.
 10. (canceled)
 11. (canceled)
 12. (canceled)
 13. (canceled)
 14. (canceled)
 15. In combination with a quick-coupler including a first coupler section defining a receptacle and a second coupler section defining an insert which is received in the receptacle when the coupler is connected together, a centering assembly for guiding said first and second coupler sections into axial alignment along a connection axis when the coupler sections are disconnected from each other and being moved together for connection comprising: one of said first and second coupler sections being disposed such that an associated one of said receptacle or insert is centered along said coupling axis; said one of said first and second coupler sections including a centering member having an outwardly facing centering surface disposed in centered relationship to, and being tapered toward, said coupling axis in a direction toward another of said first and second coupler sections; said another of said first and second coupler sections including a second centering member having an inwardly facing centering surface shaped complimentary to said outwardly facing centering surface, with said second centering member being coupled in leading relationship to an associated receptacle or insert of said another of said first and second coupler sections, as considered with respect to said another of said first and second coupler sections moving toward said one of said first and second coupler sections, whereby contact between said outwardly and inwardly facing centering surfaces will result in said another of said first and second coupler sections being guided into axial alignment with said one of said first and second coupler sections.
 16. The combination, as set forth in claim 15, wherein said outwardly facing centering surface includes a frusto-conical section, and wherein said second centering member includes a plate disposed substantially perpendicular to said connection axis and containing a frusto-conical opening defining said inwardly facing centering surface. 